Building floor construction and underfloor wiring duct system



Aug. 9, 1966 J.'w. HUDSON BUILDING FLOOR CONSTRUCTION AND UNDERFLOOR WIRING DUCT SYSTEM Mw Mw. 1/ @l w w R m u j J w @u s. i mw .m /y A N NWN( M m www A d 2 www www www m ww www M www www www www m J e ww .Q mmm m? m mi i @w f mm m u m H H H HT FSW IHM u H n u l u E l m -lim E l\ Mw w ww www \.\s\ ww Www if ,www $1 @1 N m I wf 1 z I f Jg A. EFW: .WW1 ||1| i MMWMM IM m P;E; m w Sm wm .BQ www www Mm Aug. 9, 1966 .1. w. HUDSON 3,264,791

BUILDING FLOOR CONSTRUCTION AND UNDERFLOOR WIRING DUOT SYSTEM 2 Sheets--Sheerl 2 Filed Maron 4, 1963 IN VENTOR.

; @uw .M

United States Patent O 3,264,791 BUILDING FLOOR CONSTRUCTION AND UNDER- FLOOR WIRING DUCT SYSTEM James W. Hudson, Lexington, Ky., assignor to Square D Company, Park Ridge, Ill., a corporation of Michigan Filed Mar. 4, 1963, Ser. No. 262,445 4 Claims. (Cl. 52-221) This inventi-on relates to the construction of an abovegrade concrete floor and to an underfloor duct system embedded therein for housing wiring for telephones and electric power.

Multi-story buildings formerly were built with loadbearing exterior walls and many load-bearing interior Walls. Since the load-bearing capacity of such structures was very high, floor weight was not of primary concern, and the above-grade floors were relatively thick slabs of concrete. Underoor wiring duct systems were easily embedded in the thick slabs.

Many newer buildings are supported by interior columns to permit the use of exterior curtain walls and the elimination of load-bearing interior walls. Weight has thus become a more important factor, and the concrete slabs of upper oors have been made thinner. At the same time, increased lighting -requirements and greatly expanded use of telephones and electrically powered office equipment have brought a demand for more underoor wiring raceways in the thinner concrete floors.

Cellular steel floors have been used to meet this demand. However, many `architects and engineers prefer oors of reinforced concrete instead of cellular steel oors because of the inherent resistance to lire, better acoustical properties, greater local availability, lower cost, and increased stability of reinforced concrete. Prior to the present invention, architects and engineers who preferred reinforced concrete floors met the demand for more wiring raceways in the thinner concrete slabs by using a complete grid of junction boxes and single level underfloor wiring duct throughout the entire area, the junction boxes being spaced apart from each other in parallel spaced -rows and cross-connected in mesh fashion by wiring duct all at a single level for accommodation in a thin concrete floor slab.

Such an underfloor duct system is not only very expensive, but has inadequate wire carrying capacity in certain portions. Inadequate wire carrying capacity occurs because a junction box in a run of distribution duct nearest a wire distribution center must accommodate not only the wires for that run, but also the wires for the run of distribution duct farthest from the wire distribution center and those for all intervening runs.

The present invention overcomes this problem by providing an underfioor duct system comprising a plurality of relatively closely spaced parallel feed duct runs connected to a housing for a wire distribution center and extending transversely of and underneath a plurality of more widely spaced distribution duct runs, the feed duct runs extending successively farther from the housing and each feed duct -run being connected to a respective group of successively spaced distribution duct runs, the respective groups `of distribution duct runs being spaced successively farther from the housing in correspondence wtih the successively farther extent of the feed duct runs. This results Patented August 9, 1966 in a pyramidal effect and hence the duct system of this invention can be termed a pyramidal feed system.

The present invention involves the foregoing pyramidal arrangement of feed duct runs at one level and distribution duct runs at another'level, together with a concrete floor construction wherein most of the floor is of a thickness sufficient to encase the distribution duct runs and the upper portions of the junction boxes but not sufficient to encase the feed duct runs and the lower portions of the junction boxes, and relatively narrow and widely spaced dropped concrete beams depend from the rest of the floor solely for providing sufficient thickness to encase the feed duct Iruns and the lower portions of the junction boxes. The additional thickness of concrete necessary to form the relatively narrow and widely spaced feeding beams which enclose the feed duct runs and the lower portions of the junction boxes does not significantly increase the load required to be supported by the interior columns of a building.

An object of the invention is to provide an improved underfloor wiring duct system.

Another object is to provide an improved concrete floor construction and underfloor wiring `duct system for the above-grade floors of a multistory building.

These and other objects will become apparent when the following specification is considered along with the accompanying drawings in which:

FIGURE 1 is a plan View of a portion of an underfloor duct system constructed in accordance with this invention, showing the duct before the pouring of a concrete floor thereover and schematically illustrating the junction boxes by solid black areas;

FIGURE 2 is a sectional view of a portion of a concrete oor having an underlloor duct system constructed in accordance with -this invention embedded therein, the section through the underfloor duct system being taken substantially along the line 2-2 of FIGURE l and enlarged from the scale of FIGURE l though still smaller than actual size; and

FIGURE 3 is a perspective view of a portion of an underfloor duct system constructed in accordance with this invention.

FIGURE l represents a portion of an underfloor duct system for an above-grade floor of a multi-story building having an outer wall 10. A housing or cabinet 12 for a distribution center for electric power supply wires and a housing or cabinet 14 for a distribution center for telephone service wires are provided adjacent the wall 1f). Extending parallel to the wall 10 on a first upper level are a plurality of pairs of runs of distribution duct. The two distribution duct runs of each pair are relatively closely spaced and the pairs of distribution duct runs are relatively widely spaced. A duct run 16p of each pair of distribution duct runs houses electric power supply wires and a duct run 1612 of each pair houses telephone service wires. The electric power supply wire distribution duct runs 16p are connected with the cabinet 12 by a feed duct run 17p extending on a second lower level underneath and transversely of the distribution duct runs 16p on the first upper level and connected to the distribution duct runs 16p respectively by a plurality of junction boxes 18p. The telephone service wire `distribution duct runs 161? are connected with the cabinet 14 by an arrangement of feed duct runs which comprises the i pyramidal feed system of my invention.

Because of the probable eventual use of a large number of telephones in a building, and the possible use of special telephones having extremely complex circuitry and requiring an unspliced cable app-roximately one inch in diameter for each telephone, a lplurality of parallel feed duct runs 20t, 21t, 22x, 2315, 24t extending from the cabinet 14` and spaced as closely together as practicable is provided. In

the example shown, each of the feed duct runs 209241,

extends on the second lower level underneath and transversely of the distribution duct runs 16ton the first upper level and is connected to a group Vof three successive juncgroups and having other wires therein, and thus the wire carrying capacity Vis greatly increased and the job of lishing wires through the duct system is greatly facilitated. It will be understood that the building has another exrterior` wall opposite the wall 10, that the -pairs 16p and 16t of the distribution duct runs are spaced uniformly across the oor between the wall 10 and the opposite wall, and that `a pyramidal .feed arrangement symmetrical to that just `described with respect to the. [feed duct runs v201t-24t andgroups of junction boxes ltmay be provided to extend Ifrom another `:telephone cabinet opposite the cabinet 14, and that the feed duct run 17p may extend across the` oor to another electrical cabinet opposite the cabinet 1-2.

yand connect to other junction boxes 18p in addition to those shown. The pyramidal lfeed arrangement is normally provided only for the telephone service wires, a single duct run such as 17p connected t-o all the junction boxes 18p` extending across `a floor normally furnishing adequate wire carrying capacity for all the electric power supply wires in a particular floor area. However, it is obvous thatthere 'could be a pluralityY of feed duct runsfor electric power supply wiresarranged in a pyramidal feed system similar t-o that of the feed .duct runs 20l-2'4t.

Because the feed duct runs 17p and 20t-24t extend under the distribution `duct runs 16 yand 16t, the concrete oor must be thick enough to enclose two levels of duct. However, if the Whole floor were made thick enough to enclose two levels of duct, the load required to be carrm` by the interior columns would be too great. To solve this problem, feeding beams are provided in accordance with this invention as a complement to the above-described pyramidal -feed undertlioor duct system.

Because of the arrangement of separate groups of only three junction boxes 181 with each group having a separate feed duct run from the ,cab-inet 14, telephone service Wires from an area extending a considerable distance on Aopposite sides of the feed Iduct runs 20t-242t can be ac- A commodated. Thus if a oor extends several hundred feet in the direction of the distribution duct runs 16p.` and 16t, a plurality of sets of cabinets 12and 14 may be provided along each of a pair of opposite outer walls otf a 'building and the sets may be spaced a considerable distance apart, and corresponding sets of feed duct runs 17p p and 20t'-24t may also be spaced a considerable distance (for example, approximately fifty feet) apart. Between the sets of feed duct runs 17p and 20t24t and thus for the materially greater portion of the floor area the concrete lioor may be made of a thickness sufficient to enclose only the distribution duct runs 16p and 1611.

The feed duct runs 17p and 20t-24t..are formedof blank duct, and the distribution duct runs `16p and Vltt are formed of duct having access inserts spaced uniformly along the top thereof, as shown in FIGS. 2 and 3.

The thickness of the greater portioniotf theoor area may be as indicatedat the portions 27` at opposite ends of the door section shown in FIG. y2. At' widely spaced inter-` vals, small portionsi of :the ffloor may be made thickerby the provision of transversely-extendingdropped feeding Y beams 28 solely `for enclosing the feed duct runs 17p ,and 20t.24tand the lower portions of the junction boxes 11817 v Because of the pyramidaltfeedarrangement ofj this invention, the feeding beams f8 may be widely spaced,

and their additional weight added to the weight of a door entirely of the thickness of the portions27 is a relatively insigniiicant'increase in the loadV required to be supported by the interiorcolumnsof abuilding.k By way lof example, the thickness of the portions 27fof-a lfioor may be three inches, While'the -totalthickuess -in the sections havingthe additional dropped .fee-ding ,beams 28 may be live inches. Further, various of the ,junction boxes 18p may have -a conduit such as a conduit 30 las shown :in `FIG. 2

extending downwardly therefrom for housing electric power supply wires for ceiling lights in roomsv below the par-v It should be noted that each junction box 18p contains only the .relativelyy high voltage electnic power supply wires, and that eachljunction box 18tfcontainsf-only telei phone and other low voltage wires.

Various modifications may; bewmade. -inY the: structure disclosed withoutdeparting from the spirit tand scopeof the invention.

What is claimed is:

- 1.,An undeniloor wiring duct` systenrfor distributing l electrical service wires from ahousing, said underfloor wiring duct system comprising (a) -a plurality of 'parallel electrical Wiring feed duct runs off different lengths connected to the housing and i` extending different distances therefrom at a rst level, (b) `a corresponding plurality of groups of lelectrical wiring distribution r-duct-v runs extending `transversely of said feed ductruns Vat a second level, each 'of said i` distribution duct. runs khaving a plurality of access -openingsspaced longitudinally therealong for distributingelectrical "service wires to door outlets, all the distribution duct runs ofanygroup being spaced :farther from the housing than the distance .any of the distributionduct Iruns of -a group ,closer to the housing is spaced from lthe housingaeachfeed duct run lbein-g connected to each distribution duct run off a respective one of said groups of distribution duct runs, and each-feed duct run being .connected to `'only those distribution .duct runs of its` respective Vgroup.

2.1 An underfloor wiring duct system as claimed in claim 1, wherein said feed duct runs-are disposed beneath said f Idistribution duct vruns at the lower yof saidrst and second 2 levels.

3J The combination of'a concrete floor for an abovegrade floor of a multi-story building and an undentloor wiring duct system embedded therein yfor distributing electrical service wires from a housing, said combination comprising` (a) a plurality of ,parallel-electrical wiring feed-ductk runs of different lengthsconnected to the housing and i" extendingV different Idistances therefrom at la lower first level,

(Ib) a corresponding plurality of groups of kelectrical wiring vdistribution iductr runs extending Atransversely of said feed `ductruns at an upper second level, each of the distribution ductruns of :a group closer tol the i housing is spaced .from the housing, each Vfeed duct run being connected to each distribution duct run olf References Cited by the Examiner a respective one of said groups oi distribution duct UNITED STATES PATENTS runs, and each feed duct run being connected to only .duct uns exposed, and 2,944,478 7/ 1960 Curran 52-221 X (d) a dropped concrete beam depending integrally from 2,946,413 7/ 1960 Wilesmann 189-36 0f Said feed'ductruns- 1o FOREIGN PATENTS 4. A combination concrete oor and underlloor wiring `duct system as claimed in claim =3, wherein said distribu- 674711 6/1952 Great 'Bumm' tion duct runs are relatively long and a plurality of sets FRANK L ABBOTT primary Examiner.

of feed duct runs and dropped concrete beams are proy 'vided and spaced relatively far apant longitudinally of said 15 HENRY C' SUTHERLAND Exammer' vdistribution duct runs. I. L. RIDGILL, Assistant Examiner. 

1. AN UNDERFLOOR WIRING DUCT SYSTEM FOR DISTRIBUTING ELECTRICAL SERVICE WIRES FROM A HOUSING, SAID UNDERFLOOR WIRING DUCT SYSTEM COMPRISING (A) A PLURALITY OF PARALLEL ELECTRICAL WIRING FEED DUCT RUNS OF DIFFERENT LENGTHS CONNECTED TO THE HOUSING AND EXTENDING DIFFERENT DISTANCES THEREFROM AT A FIRST LEVEL, (B) A CORRESPONDING PLURALITY OF GROUPS OF ELECTRICAL WIRING DISTRIBUTION DUCT RUNS EXTENDING TRANSVERSELY OF SAID FEED DUCT RUNS AT A SECOND LEVEL, EACH OF SAID DISTRIBUTION DUCT RUNS HAVING A PLURALITY OF ACCESS OPENINGS SPACED LONGITUDINALLY THEREALONG FOR DISTRIBUTING ELECTRICAL SERVICE WIRES TO FLOOR OUTLETS, ALL THE DISTRIBUTION DUCT RUNS OF ANY GROUP BEING SPACED FARTHER FROM THE HOUSING THAN THE DISTANCE ANY OF THE DISTRIBUTION DUCT RUNS OF A GROUP CLOSER TO THE HOUSING IS SPACED FROM THE HOUSING, EACH FEED DUCT RUN BEING CONNECTED TO EACH DISTRIBUTION DUCT RUN OF A RESPECTIVE ONE OF SAID GROUPS OF DISTRIBUTION DUCT RUNS, AND EACH FEED FUCT RUN BEING CONNECTED TO ONLY THOSE DISTRIBUTION DUCT RUNS OF ITS RESPECTIVE GROUP. 